1. Field
This patent specification describes a high speed image processing method and apparatus which implements a batch process for a plurality of source image objects. This patent specification also describes a program product of the method, a computer readable medium having the program product, and an image forming system having the apparatus.
2. Discussion of the Background
In response to an increasing demand for a high resolution and speed, improvements to printing systems such as a page printer have been made mainly by implementing advanced CPUs (central processing unit). It has been difficult, however, to satisfy the demand merely by the CPU performances although the development of high performance CPUs has been rapid. Especially, a color printing system such as a color laser printer needs to perform a variety of image processing including an image zoom for C, M, Y and K type images, a dither processing and a color translation processing.
Owing to the recent development of semiconductor technology, a specific hardware accelerator becomes capable of performing a part of the image processing of the printing systems which is conventionally performed by the CPU. For example, some of the printing systems employ the above-mentioned hardware accelerator in a form of an FPGA (field programmable gate array) so that a change of image processing functions may easily be taken place.
However, the performance of the hardware accelerator is still not sufficient to meet the demand for the high resolution and speed on the image processing of the printing system. Accordingly, it is yet difficult to allocate a sufficient number of high speed memories to a halftone generation which particularly requires a high speed
One attempt to respond to the above-described demand for a high resolution and speed uses a threshold-value-matrix page memory and reads. In this attempt, threshold data are stored line by line into registers for a repetitive use when they are read from the threshold-value-matrix page memory. Then, the threshold data are selectively sent to a plurality of comparators and are subjected to a plurality of parallel comparisons. After that, the threshold data stored in the registers are sequentially shifted line by line for a repetitive use.
In this attempt, however, either one of the image zoom and the halftone generation under processing is inevitably required to be stopped in a system having a single main memory system with no extra memory for dither data, when these two functions are performed at the same time.